Biostratigraphic Potential Research Articles

Biostratigraphic potential of dinoflagellate cysts recovered from the Late Jurassic ammonites of the Tethys Himalaya, India

Biostratigraphic potential of dinoflagellate cysts recovered from the Late Jurassic ammonites of the Tethys Himalaya, India

Rhopaliophora? asymmetrica, a new acritarch species from the lowermost ‘Arenig’ of Baltica and its biostratigraphic potential

A shallow water analogue of the basal part of the stratotype for the ‘Second stage’ of the Lower Ordovician at Diabasbrottet, Mt. Hunneberg, Sweden, occurs in the Baltic Basin, in the St. Petersburg region, northwestern Russia, where it is represented by the Lakity beds of the lower Leetse Formation, Hunneberg Substage. Palynological investigations of these beds revealed a diverse acritarch association comprising several distinctive species with high biostratigraphic and palaeobiogeographic potential, ranging throughout the upper Tremadoc–lower Arenig interval. Rhopaliophora? asymmetrica sp. nov., which characterises the Leetse Formation, is described from levels independently dated by co-occurring graptolites (Tetragraptus phyllograptoides Zone) and conodonts (Paroistodus proteus–Prioniodus elegans Zones). The possible significance of this species for the recognition in Baltica of the base of the ‘Arenig’ (base of the ‘Second stage’ of the Lower Ordovician Series) is discussed.

Selachian scales from the Cenomanian (Late Cretaceous) of Bathurst Island, northern Australia

Seven selachian scale types are described from the middle Cenomanian Moonkinu Formation, outcropping on the southern shores of Bathurst Island in northern Australia. The scales are classified in accordance with previously published scale morphologies of Cretaceous and modern sharks, and are representative of the Orders Squatiniformes (Family Squatinidae), Carcharhiniformes (Family Scyliorhinidae), and Lamniformes (Family Odontaspididae). The presence of typically bottom-dwelling, shallow-water angelsharks (squatinids), catsharks (scyliorhinids), and sand tiger sharks (odontaspidids) within the Moonkinu Formation support an inner neritic depositional environment interpretation for the unit, previously determined from foraminiferal biofacies and lithology. The biostratigraphic potential of these scales can only be assessed after scales from more Cretaceous localities are described and documented.

Biostratigraphic potential of Middle Cambrian hyoliths from the eastern Georgina Basin

Fourteen hyolith taxa are documented from the Middle Cambrian (Templetonian to Floran) of the eastern (Queensland) portion of the Georgina Basin, Australia, as a contribution toward a prospective Australian Cambrian hyolith biozonation. The described fauna is from the Beetle Creek Formation (including Monastery Creek Phosphorite Member) and Gowers Formation. Additionally, the enigmatic Cupittheca and some indeterminate hyoliths are figured to illustrate aspects of hyolith morphology. Guduguwan hardmani, widespread in Ordian-early Templetonian strata of northern Australia, is here recorded from the early Templetonian of the eastern Georgina Basin. A new family Gakidae is established for sulcavitide hyolithomorphs with a conch of pentagonally tabernacular transverse section, to include Gaka, Kalkatungu gen. nov. and possibly Dorsolinevitus. New genera are the hyolithid Yalarrnga mara gen. et sp. nov., sulcavitid Kulangarra kutjurru gen. et sp. nov., gakid Kalkatungu murlu gen. et sp. nov. and angusticornid Yuku tjurtu gen. et sp. nov.; new species are Loculitheca kunka sp. nov., Carinolithes tjikilirri sp. nov., ?Sololites kankari sp. nov., ?Shandongolithes thakal sp. nov., ?Gerkella thuka sp. nov. and ?Yacutolituus rakatju sp. nov. Taxa in open nomenclature are Foersteotheca cf. dubecensis, ?Holmitheca sp. and ?Dorsojugatus sp. On present knowledge, the potential for an Australian Cambrian hyolith biozonation is limited in the Early Cambrian, but for the Middle Cambrian, G. hardmani is a widespread Ordian-early Templetonian indicator, while hyolith distribution in the Monastery Creek Phosphorite Member suggests a faunal turnover at or about the incoming of Acidusus atavus which may provide a basis for biozonation in the Floran stage.

PALEOBIOLOGY OF THE NEOPROTEROZOIC (UPPER RIPHEAN) SHORIKHA AND BUROVAYA SILICIFIED MICROBIOTAS, TURUKHANSK UPLIFT, SIBERIA

Abstract Diverse assemblages of silicified microfossils have been detected in lenses of black chert within peritidal carbonates of the Neoproterozoic (Upper Riphean) Shorikha and Burovaya formations, Turukhansk Uplift, northeastern Siberia. These microbiotas are represented by 19 species of simple filamentous and coccoidal microfossils, multicellular trichomes, and thick-enveloped sphaeromorphic and acanthomorphic acritarchs. Microfossils include both prokaryotic (possibly cyanobacterial) and eukaryotic (mainly phytoplanktonic) microorganisms. The eukaryotes in these formations are relatively diverse—the result of an explosive radiation near the Meso-Neoproterozoic boundary. The discovery of abundant phytoplanktonic microorganisms in the Shorikha and Burovaya cherts increases the biostratigraphical potential of Proterozoic silicified microbiotas and fills a gap in the paleontological record of the Turukhansk Uplift, a potential candidate for the stratotype of the Meso-Neoproterozoic boundary. The affiniti...

The messaoudensis-trifidum acritarch assemblage (Ordovician: late Tremadoc–early Arenig) of the Barriga Shale Formation, Sierra Morena (SW-Spain)

The “ messaoudensis-trifidum acritarch assemblage” is currently considered to be characteristic of latest Tremadoc–earliest Arenig cold-water environments on the periphery of Gondwana, at high latitudes in the southern hemisphere. An integrated biostratigraphical study on both acritarchs and graptolites was until now only available for localities in northwest England. Reinvestigation of the “ messaoudensis-trifidum acritarch assemblage” from the Barriga Formation (Sierra Morena, southwestern Spain), which contains some graptolite horizons that can be attributed to the latest Tremadoc (pre- phyllograptoides and pre- approximatus graptolite biozones), strengthens the biostratigraphical potential of the “ messaoudensis-trifidum assemblage”, and the importance of some of the acritarch taxa recovered from these levels. It is concluded that the acritarch genera Coryphidium Vavrdová, 1972, Peteinosphaeridium Staplin et al., 1965 emend. Playford et al., 1995, Striatotheca, Burmann, 1970, and the Veryhachium lairdii group (rectangular veryhachiids) appear in the latest Tremadoc, and should not be considered as indicators of the base of the Arenig, as previously suggested.

A Lower Ordovician (Arenig) radiolarian fauna from the Ballantrae Complex, Scotland

Synopsis Recent examinations of Lower Ordovician (Arenig) cherts from the Ballantrae Complex, Scotland have resulted in the discovery of a moderately well-preserved radiolarian assemblage. Elements of the fauna are distinctive indicating that even early radiolarian forms have excellent biostratigraphic potential. The abundance of radiolarians in chert and the ease with which they can be extracted suggest that they are a potentially valuable tool for use in investigations into the timing of the development of Early Palaeozoic orogenic systems. A new family of Radiolaria the Proventocitiidae fam. nov., previously informally described from Spitsbergen (Fortey and Holdsworth 1971), is formalized herein. One new species, Proventocitum holdsworthi, sp.nov., is described; Proventocitum sp.A is described under open nomenclature.

Ordovician microvertebrate remains from the Amadeus Basin, central Australia

ABSTRACT Microvertebrate remains are described from five formations (Pacoota Sandstone, Horn Valley Siltstone, Stairway Sandstone, Stokes Formation, Carmichael Sandstone) in the Ordovician sequence of the Amadeus Basin, central Australia. Two new genera and species are erected for scales and other elements with distinctive morphology and histology. Other material is referred to indeterminate species of the agnathan genera Arandaspis and Porophoraspis previously described from central Australia, and Sacabambaspis previously described from the Ordovician of Bolivia. The most common vertebrate from the Stokes Formation is referred to Areyonga oervigi, gen. et sp. nov., a form taxon provisionally assigned to the Chondrichthyes. Scales of this species apparently lack a base, and are made of an atubular laminar surface tissue of uncertain histology. Mode of scale growth was similar to that of the Early Devonian form Polymerolepis. If correctly interpreted, this taxon is the oldest chondrichthyan and/or gnathostome known from the fossil record. The form taxon Apedolepis tomlinsonae, gen. et sp. nov. contains scales with possible osteocyte spaces in the basal tissue, and a crown composed of dentine covered with an enamel-like surface layer which also lines chambers of a pore canal system. Affinity to arandaspidid pteraspidomorphs may be indicated by a similar system of pores opening to the surface. A pore-canal system, and bone rather than aspidin, may have been primitively present in agnathans. Indeterminate remains from the early Arenig and Caradoc (Horn Valley Siltstone, Stokes Formation) may include endoskeletal ossification. These new microvertebrate faunas are assigned to four assemblages ranging in age from early Arenigian to Caradocian (Bendigonian-Eastonian). They have biostratigraphic potential for age control in Ordovician marginal marine sediments, and are important in demonstrating new combinations of hard tissue types at the beginning of the vertebrate fossil record.

Annotated bibliography of fossil radiolarian occurrences in the British Isles

A bibliography of radiolarian occurrences in the British Isles is here compiled and annotated. Over 50 entries are listed which refer to British radiolaria. Radiolaria occur throughout the Phanerozoic of the British Isles, with their main occurrences in the Ordovician of the Southern Uplands of Scotland and Northern Ireland, the Carboniferous Culm Measures of southwest Britain, the Carboniferous Limestone of various localities, the Late Jurassic (Kimmeridgian in particular) of Dorset and Scotland, the Cretaceous Chalk of southern and eastern England, and the Eocene London Clay of southern England. The occurrence of British radiolaria is well-documented through studies published around the turn of this century, but the taxonomic composition of the faunas, in modern terms, is not clearly known. It is suggested that modern taxonomic studies be undertaken in order to evaluate the biostratigraphic potential of British radiolaria.

The trilobiteCalodiscus lobatusfrom the Lower Cambrian of Scania, Sweden

Abstract Calodiscus lobatus (Hall 1847) is described from the Lower Cambrian Holmia kjerulfi Assemblagezone (lower Gislöv Formation) at Brantevik in southeast Scania (Skåne), southern Sweden. It is a geographically widespread species in the North Atlantic region, and it has been recorded from deposits representing a diversity of marine environments. The biostratigraphical potential of C. lobatus is briefly discussed, and it is concluded that it appears to be a rather long-ranging species in the upper Lower Cambrian.

Oligocene through Palaeogene/Neogene boundary foraminifera of the northern Mesohellenic Basin (Macedonia, Greece): biostratigraphy and palaeoecologic implications

Foraminifera of the Oligocene and early Miocene siliciclastic units from the northern part of the Mesohellenic Basin (Macedonia, northern Greece) provide good biostratigraphic potential. Taxa identified from a number of sections cropping out in the study area indicate that these deposits fan in Zones P20 (upper part), P21, P22 and most of Zone N4 of Blow's zonal scheme. The occurrence within the lowest part of the Pendalofos Formation of abundant Globigerinoides primordius, together with other earliest Miocene planktonics, defines the base of the Miocene. Although a remarkable planktonic foraminiferal turnover occurred close to the Palaeogene/Neogene boundary, the benthic populations do not show any clear change, except in relation to palaeoecologic conditioning. Analysis of benthic foraminifera led to the definition of a palaeodepth curve indicating that the deposition during the late Oligocene and early Miocene occurred in a middle to upper (mostly) bathyal and outer neritic conditions. The distribution of selected benthic foraminifera is compared with sedimentologically derived depositional environments. The correlation between the major global unconformities predicted by the Exxon coastal onlap chart and the Mesohellenic succession is based on the joint use of biochronologic and biostratigraphic/palaeoecologic tools.

Evolutionary trends and biostratigraphic potential of selected radiolarian taxa from the Early Carboniferous of Germany

A large number of well preserved radiolarian faunas have been found in Early Carboniferous rocks ( Pericyclus-Alpha to Goniatites-Stufe) of the “Rheinisches Schiefergebirge” and the Frankenwald (Germany). The growing number of fossil faunas makes it possible to show evolutionary tendencies of certain taxa within these stratigraphic levels. In the course of the Early Carboniferous a continuous transformation of the general character of the radiolarian faunas took place. This transformation generally tended towards an increase of the surface area of the skeletons. We see trends within the following groups. The Entactiniidae Riedel 1967 show two separate tendencies, one being a considerable lengthening of their spines, the other being a reduction of spine-number connected with a strong increase in size of the remaining spines. The Albaillellidae Deflandre 1973 show a documentable change in the morphology of their cavea as well as their stapia. The Latentifistulidae Nazarov and Ormiston 1983 evolve from ancestral narrow-rayed forms to broad-triradiate and triangular forms. The “phacoid” forms of the group Sphaerodiscus Won 1983/ Eostylodictya Ormiston and Lane 1976 show a progressive overgrowth of the central shell by peripheral concentric rings and a simultaneous change in morphology from flat-discoidal to lensoid.

The Complex Chorate Dinoflagellate Cysts of the Bathonian to Oxfordian (Jurassic): Their Taxonomy and Stratigraphic Significance

The Complex Chorate Dinoflagellate Cysts of the Bathonian to Oxfordian (Jurassic): Their Taxonomy and Stratigraphic Significance

Trends in the development of Paleozoic Radiolaria

Radiolaria may be the only planktonic or nektonic faunal group which has clear biostratigraphic potential and which is known from deposits of all Phanerozoic systems. In fact, until recently, it was assumed that they were even typical components of the Precambrian biosphere. An understanding of the kinds of evolutionary trends exhibited by Paleozoic forms can provide a useful background against which subsequent radiolarian evolution can be better understood. Realizing that it is impossible to prepare an exhaustive survey, we have tried to emphasize developmental trends which affect more than one Paleozoic group so as to identify tendencies which may have more general significance. It is suggested that such general tendencies include: (1) recurrent trends toward lightening of the shell mass, accompanied by increased complexity of shell construction; (2) transformation of the structure of the internal framework which markedly affects the form of the external shell; (3) the development of multiple internal shells through tangential rather than radial growth; and (4) the occurrence of rapid radiations following the appearance of new shell forms (e.g., Albaillellaria, stauraxon polycystines) which are presumed to confer some selective advantage.

Origin and biostratigraphic potential of the stauraxon polycystine Radiolaria

An attempt is made to identify the evolutionary processes involved in the origin of the Palaeozoic stauraxons which appear abruptly in the Early Carboniferous without obvious predecessors. We posit that (1) the development of a heavy spongy layer around external spines in Late Devonian entactiniids such as Tetrentactinia Foreman, 1963, provided new configurations for selection to work on, (2) there was a strong selective pressure for the development of flattened, extensiform shells, as the reduced sinking rate of such shell shapes is a distinct advantage for planktonic life, (3) the internal framework developed by internalization of formerly external spines coupled with the reappearance of an archaic inner sphere to this framework which was co-selected by mechanical requirements for a strong inner framework to support the extensiform outer shell, (4) a spongy layer became the new outer shell, and (5) the success of this new form allowed the rapid radiation of stauraxon geometries that we see in the Late Carboniferous through Permian. Although an informed opinion may require a more complete knowledge of possibly annectant Triassic forms, we are presently skeptical of phylogenetic connection between Palaeozoic stauraxons, which underwent a marked extinction at the end of the Permian, and the Mesozoic forms of the Hagiastridae sensu Baumgartner, 1980 and Patulibracchiidae Pessagno, 1971. A comparison of the arm cross-section among these groups is to a certain extent inconclusive, but the tendency among Permian stauraxons away from the hagiastrid type of arm structure makes us suspect a lack of phyletic connection.

Fossil Molluscan Larvae: A New Biostratigraphic Tool

Fossil molluscan larvae are less facies dependent and have a wider geographic range than their adult counterparts. They are also easily recovered from cores and small samples. With proper documentation, the study of fossil larvae can considerably enhance the biostratigraphic potential of macrofossils.

Inocérames

The first inoceramids appeared during the Early Jurassic (Lias). The group did not begin to diversify markedly until the Middle Turonian. The biostratigraphical potential of the group is somewhat impaired by taxonomical reasons. The paper summarizes stratigraphical information from Albian to Turonian of Europe.

Cenozoic Deep-Water Benthic Foraminifers: ABSTRACT

Cenozoic deep water deposits have yielded rich and diversified faunas of benthic formaminifers. From still limited data, it is clear than these faunas were depth stratified and that most species were cosmopolitan in distribution. The wide distribution and species richness, together with faunal turnover, which in places was very abrupt, points to great biostratigraphic potential. High turnovers delineate distinct Paleocene, Eocene, and Oligocene-early Miocene faunas. A gradual but profound wave of extinction and speciation occurred during the middle Miocene and by late Micene had created the modern deep water faunas. Superimposed upon these evolutionary developments are strong changes in depth preference, particularly among those species that persist across the turnover periods. During the Paleocene-Eocene transition some species became restricted to the bathyal realm while others preferred the abyss. During the Eocene-Oligocene transition a net downward depth range extension of bathyal species occurred. During the late Miocene the periodic vertical migrations of bathyal and abyssal faunas that so strongly characterize the Quaternary began to appear. In the North Atlantic, such depth range excursions may extend over more than 1,500 m. The evolutionary and bathymetric changes of benthic faunas are their response to the evolution of the deep water environment, particularly the establishment of the cold water sphere during the late Eocene, and the addition of the North Atlantic as a source of cold water during the middle Miocene. The late Cenozoic depth changes are indicative of periodic rearrangements of the deep ocean circulation in response to climatic change at the earth's surface. End_of_Article - Last_Page 987------------

Biostratigraphic Significance of Fossil Molluscan Larvae: ABSTRACT

Most marine mollusks have some form of pelagic larval stage which produces a distinctive protoconch. Scanning electron microscope studies reveal that larval shells are routinely preserved in sediments as old as the Upper Cretaceous, and that protoconchs are characteristic enough to identify to species on the basis of the unmetamorphosed larval shell. This has paleoecologic and biostratigraphic potential in cores where only a few identifiable adult mollusks are normally found. In addition, larval shells are carried by water currents to areas not inhabited by the adults, extending the species geographic range and partly eliminating facies dependence. Fossil mulluscan larvae are, therefore, a potentially valuable new micropaleontologic group. End_of_Article - Last_Page 1558------------

The biostratigraphic potential of Precambrian stromatolites

The morphology of stromatolites is controlled partly by the biological composition of algal mats and partly by the direct action of environmental factors. Both trapping of detrital grains and precipitation of carbonate in algal mats are important processes in stromatolite formation. Precambrian stromatolites were probably not subject to the environmental restrictions of Recent stromatolites. Stromatolites can be classified on the basis of a number of morphological features, some of which relate directly to the biological characteristics of algal mats (lamina shape and microstructure) and some of which have at least partial environmental control (e.g., column shape, branching style). The taxonomic significance of characters may vary in different taxa. A binomial (but not biological) form nomenclature is applied, using “groups” (analogous to genera) and “forms” (analogous to species). The biostratigraphic potential of Precambrian stromatolites, theoretically possible from what is now understood of the controls of Recent stromatolite morphology, can only be tested empirically by determining the time ranges of defined taxa. This relies heavily on other means of dating and correlation. Initial results of stromatolite biostratigraphy in Australia proved encouraging and appeared to confirm the applicability of the biostratigraphic scheme worked by Russian geologists. However, none of the stromatolite assemblages described from Australia is identical to any from the U.S.S.R.: none contains all of the elements described from the Russian assemblages, and most of the common elements are comparable only at group level. New data suggest that the time ranges of several groups are longer than previously accepted, and caution is therefore urged in using group level identifications alone as a basis of correlation. Identity of forms is a better criterion for correlation, but most forms have a limited geographic distribution. Further systematic description and identification of stromatolites from rock sequences of all ages on all continents are needed to establish the actual time ranges of taxa and assemblages of taxa, and hence their biostratigraphic applicability. Stromatolite assemblages presently known from various Proterozoic basins of Australia are discussed. Pre-Riphean assemblages include groups previously known only from the Riphean, as well as groups not found in the younger rocks. Partial equivalents of each of the subdivisions of the Riphean occur in a number of basins, but their stromatolite assemblages are not yet well known. Late Riphean equivalents have the best documented assemblages and the groups present are generally consistent with their time ranges determined in the U.S.S.R. However, the Burra Group (Adelaidean) of South Australia lacks typical Late Riphean stromatolites and was originally correlated with the Middle Riphean. New radiometric and stromatolite data suggest that deposition of the whole Adelaidean sequence commenced during the Late Riphean.